With respect to a conventional road vehicle, a hybrid road vehicle additionally comprises at least one electrical machine that is mechanically connectable to the driving wheels, an electronic power converter that drives the electrical machine, a system for electric energy that is electrically connected to the electronic power converter, and a system for cooling the electrical machine and/or the electronic power converter. The placement of all these additional elements inside the road vehicle may be very complex, particularly in the event of a high performance sport vehicle that has very small internal spaces. Accordingly, one is often forced to arrange the operating devices of the hybrid road vehicle in positions that are not optimal.
Patent Application DE10224884A1 describes a frame for a road vehicle equipped with two door sills with an internally hollow tubular shape, so that a seat housing a group of electrical batteries is defined inside each door sill. The electrical batteries are axially inserted inside the corresponding door sill through a through aperture obtained in a rear part of the door sill. Nevertheless, once the construction of the road vehicle is complete, the accessibility to the electrical batteries housed inside a door sill is particularly difficult.